This invention relates to processing of electrical signals and more particularly to a system for transmitting low level analog signals wherein the analog signals are converted into frequency modulated light which is transmitted by means of a fiber optic bundle and the transmitted modulated light is demodulated to obtain an exact replica of the input electrical signals.
Sending of electrical signals over long lengths of wire requires bulky cables that are subjected to electro-magnetic radiation. The interference caused by electro-magnetic radiation is particularly significant in case of low level signal transmission. Old methods of low signal levels optical communication use expensive components, high voltage detectors, amplitude modulation (AM) techniques and some consume large amounts of power for useful optical links. Furthermore, most of the work in fiber optic communication has involved transmission of high frequency digital signals with a very limited amplitude dynamic range. It is thus desirable to have an optical communication system for transmission of low level electrical analog signals over an optical path which consumes a very small amount of power, uses inexpensive electronic components and has a wide dynamic range.